1. Field of the Invention
The present invention is directed to a printer ribbon cartridge device for containing and protecting printer ribbons as provided for and intended for use with various high speed printers.
2. Description of the Prior Art
A number of known type printer ribbon cartridge devices are available, but they have a number of deficiencies which not only cause printer/cartridge malfunctions but also make the cartridge difficult and awkward to load into the printer platform.
Specific deficiencies of known cartridge devices are the lack of a tension device to keep the ribbon taut during transit of the cartridge, or whenever the cartridge is not installed in the printer. Furthermore, ribbon that is not under tension, but instead is loose and unguided makes insertion of the cartridge into the printer carriage very difficult because of the small clearance between the card guide and the platen of the printer.
Another deficiency of known devices is the lack of any anti-backwind device to eliminate the possibility of accidental rewinding of the cartridge during handling thereof with the consequential result that if the cartridge is used after such rewinding the desired printing will occur with a used portion of the ribbon. Also, if the ribbon is reused the chances of snarling of the ribbon with subsequent cartridge jamming is greatly increased.
A further problem with known type cartridge devices is that a rubber belt is commonly used to provide both the drive and the slip for the ribbon take-up spool. This is an anomaly, for if more tension is required to effect a tight rewind then this same additional tension opposes the required slipping action and the belt then does not function properly as a slip clutch. A slipping clutch function is required to maintain a constant tension as the take-up spool diameter increases in size during the printing operation as the printing ribbon is being fed through the cartridge and wound up. Another design weakness in the use of a rubber belt drive is that the inherent characteristic of the rubber is to elongate under load. Also, the shelf life of the cartridge is severely limited by this physical property. That is, cartridges that function properly shortly after the initial manufacture thereof may not function properly after six months or so due to the change of the rubber characteristics and/or belt stretch.